Saturday, June 16, 2007
  In Adam's fall sinned we all ... even paddlefish.

Recent trends among evolutionary biologists are intriguing, to say the least. They are beginning to focus more on loss than on invention.

The basic idea, in a strictly limited context, is very old. It's been known pretty much forever that some types of animals are degenerate or simplified versions of earlier forms. The easiest example: Fish that live in caves gradually lose their eyes. More generally, when you find yourself a cushy niche that requires very little effort, you'll lose parts of your nervous system, musculature or limbs over many generations.

Now some geneticists are taking the idea of original perfection and original complexity far more deeply and broadly.

Quote from a New Scientist article:

The entire tree of life has been built on the assumption that evolution entails increasing complexity. So, for example, if two groups of animals were considered close because both had a particular prominent feature, then someone discovered a third line that lacked that feature but shared many other aspects of the two groups, traditional phylogenists would conclude that the feature had arisen independently in the two outlying groups, by a process known as convergent evolution. They often did not even consider the alternative explanation: that the feature in question had evolved just once in an ancestor of all three groups, and had subsequently been lost in the intermediate one. Now a handful of molecular biologists are considering that possibility.

Another example:

Last month, Marcus Davis of the University of Chicago and colleagues reported that a species of paddlefish shows patterns of gene expression during development that were previously thought to be exclusive to land-living vertebrates - in other words, those with limbs. This paddlefish is the living species that most closely resembles the bony fish of the Palaeozoic era, which lived more than 250 million years ago. Davis concludes that primitive bony fish may have had something like limbs, which were lost in their descendants.

In other words, the classic image of fish growing legs as they marched onto land doesn't make sense ... the legs were there already, even before the fish left the water.

Let's repeat that last point, as Roger Hedgecock likes to do:

* * * * * * * * * * * * * * * * * * * * * * * * * * *

THE LEGS WERE THERE ALREADY, BEFORE THE FISH NEEDED THEM.

* * * * * * * * * * * * * * * * * * * * * * * * * * *


If this turns out to be the dominant pattern, we may soon find that large and disconnected groups such as insects and vertebrates are both simplified versions of one grand blueprint.

Instead of starting with the basics and randomly adding new parts, some of which happened to work pretty well ... it's beginning to look like we all started from one big complicated genetic plan, and each type of critter skipped building the parts it didn't need. But when it came time to build a new wing (yeah, lame pun) the plan was ready and waiting.

I'm surprised that the Intelligent Design folks haven't leaped into this with both feet (or all 12 or 24 feet, or whatever the original plan specified!)

The main ID website, Discovery Institute in Seattle, doesn't have any articles on the subject.

Letting Professor Polistra have the final (Greek) word on the matter:








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Uncanny sidenote: An artist who picked up the same essential idea through a much more direct channel. Look at "Epoch" by Michael Meissner in the middle of this website.

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Polistra was named after the original townsite of Manhattan (the one in Kansas). When I was growing up in Manhattan, I spent a lot of time exploring by foot, bike, and car. I discovered the ruins of an old mill along Wildcat Creek, and decided (inaccurately) that it was the remains of the original site of Polistra. Accurate or not, I've always liked the name, with its echoes of Poland (an under-appreciated friend of freedom) and stars. ==== The title icon is explained here. ==== Switchover: This 2007 entry marks a sharp change in worldview from neocon to pure populist. ===== The long illustrated story of Polistra's Dream is a time-travel fable, attempting to answer the dangerous revision of New Deal history propagated by Amity Shlaes. The Dream has 8 episodes, linked in a chain from the first. This entry explains the Shlaes connection.

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